Compliant rolling DOF for a soft surgical module

Minimally invasive surgical instruments are evolving to fulfil the need of high dexterity and safe tissue interaction in a small workspace. The aim of this work is to implement a compliant rolling DOF to the end-effector of the STIFF-FLOP arm, which is a soft surgical manipulator. This represents a relevant improvement for the system, as most Minimally Invasive Surgery procedures require such capability for the end-effector (e.g. gripper). The authors propose a lightweight (3.3 g) device combining a soft pneumatic actuator with an origami twisting module. Multiple origami modules were made out of different flexible materials with a laser cutter. The soft pneumatic actuator reached a maximum elongation of approximately 6 mm at a pressure of 1.3 bar, generating a maximum pushing force of 12.7 N. The origami twisting module reached an angle of 54° and exerted a maximum torque of 2.5 Nmm. The analytical result and experimental tests demonstrated the high potential of the developed device.